In the Silo pneumatic conveying system, the material will pass through the bend under the  air current thrust and its own gravity. However, the material movement direction will be changed, so the material will collide several times with the bending tube, causing the wall to wear out. According to the test results, the material will collide with the pipe wall and produce more impact points in the bending tube with great curvature radius, and a similar pit can be found in the corner. In the short curvature radius bend, the wall is protected by the ability to reduce the impact of material on the pipe wall because of the large amount of material stored in the bend. In addition, as the flow rate of materials near the inner wall of the tube is slowed down, thus the wear of the wall will be reduced. It can be seen that in pneumatic conveying system, the bending wear is mainly composed of friction wear and impact wear.

Methods to enhance the wear resistance of bend pipes
In combination with the factors affecting the abrasion resistance of the bending pipe, the corresponding measures can be taken to enhance the wearability of the bending tube. First of all, In factors of selecting bend materials, it should also choose wear-resistant materials such as metal ceramic composites, thus reducing the roughness of the inner wall of the bending tube, thus reducing the wear and tear of the pipe. In the case of a prominent bend, it should be added to the easy replacement of the liner, or to increase the thickness of the area.

If use a round pipe, can use a thick-walled steel pipe or steel plate to weld with bend the pipe. For easy replacement, a rectangular section pipe is usually used. Secondly, in the bend structure design, should also achieve a reasonable design. If using a long radius elbow, the elbow is designed to be one bend joint connected with another bend, and then the cement mortar is used to fill the pores between the elbows, thereby extending the service life of the elbow. In the elbow shape design, can take oval elbow, spherical elbow or one end of the T-type elbow.

 By taking these shapes, it is possible to increase the flow cross section of the elbow portion so that the material is stagnated at the elbow, and thus the mutual collision between the materials is reduced. In the oval elbow, when the material go into the enlarged space, it will first spread and then shrink, and the formation of mobile dead zone, so it will not directly contact the inner wall. In addition, if the use of short radius elbow, also will form a material accumulation area, but it will not appear "cavity", so to prevent wear and tear at the same time, reduce the " material return  material" situation. From the results of the study, compared to long radius elbow, short radius elbow wear resistance was significantly better, but slightly weaker than the T-tube elbow.